tools.GetMidiNote() accepts double

#25

Author: swharden

src/Spectrogram/Tools.cs

@@ -83,7 +83,7 @@ public static int GetPianoKey(double frequencyHz)
  return (int)Math.Round(pianoKey);
  }
 
- public static int GetMidiNote(int frequencyHz)
+ public static int GetMidiNote(double frequencyHz)
  {
  return GetPianoKey(frequencyHz) + 20;
  }